# exo-hypergraph
Hypergraph substrate for higher-order relational reasoning with persistent
homology and sheaf theory. Enables cognitive representations that go beyond
pairwise edges to capture n-ary relationships natively.
## Features
- **Hyperedge storage** -- first-class support for edges that connect
arbitrary sets of nodes, stored in a compressed sparse format.
- **Sheaf sections** -- attach typed data (sections) to nodes and edges
with consistency conditions enforced by sheaf restriction maps.
- **Sparse persistent homology (PPR-based O(n/epsilon))** -- computes
topological features efficiently using personalised PageRank
sparsification.
- **Betti number computation** -- extracts Betti-0 (connected components),
Betti-1 (loops), and higher Betti numbers to summarise structural
topology.
## Quick Start
Add the dependency to your `Cargo.toml`:
```toml
[dependencies]
exo-hypergraph = "0.1"
```
Basic usage:
```rust
use exo_hypergraph::{HypergraphSubstrate, HypergraphConfig};
use exo_core::{EntityId, Relation, RelationType};
let config = HypergraphConfig::default();
let mut hg = HypergraphSubstrate::new(config);
let e1 = EntityId::new();
let e2 = EntityId::new();
let e3 = EntityId::new();
// Create a 3-way hyperedge
let relation = Relation {
relation_type: RelationType::new("collaboration"),
properties: serde_json::json!({"project": "EXO-AI"}),
};
hg.create_hyperedge(&[e1, e2, e3], &relation).unwrap();
// Compute topological invariants
let betti = hg.betti_numbers(2);
println!("Betti numbers: {:?}", betti);
```
## Crate Layout
| `graph` | Core hypergraph data structure |
| `sheaf` | Sheaf sections and restriction maps |
| `homology` | Sparse persistent homology pipeline |
| `betti` | Betti number extraction and summarisation |
## Requirements
- Rust 1.78+
- Depends on `exo-core`
## Links
- [GitHub](https://github.com/ruvnet/ruvector)
- [EXO-AI Documentation](https://github.com/ruvnet/ruvector/tree/main/examples/exo-ai-2025)
## License
MIT OR Apache-2.0